1. Field of the Invention
The present invention relates to a motion device and a moving device which relatively move moving elements along an extended orbital element such as a ball spline, a ball screw and a guide.
2. Description of Related Art
In the past, in order to move a workpiece or a tool with high accuracy in machinery such as a machine tool and various industrial machines, or in order to operate movable members with high accuracy in precision instruments or the like, according to various applications, motion devices such as ball splines, ball screws and guides of different sizes are used. In particular, recently, according to the increasing compactness of machines or mechanisms, compactness of the motion devices themselves constituting the machines are increasingly desired.
In general, the motion device includes an orbital element that is installed so as to be extended, and moving elements into which the orbital element is inserted, movably supported in the extended direction. Because rolling elements including a plurality of balls or the like are supported at the inner portions of the moving elements, the moving elements and the orbital element are capable of smoothly moving relative to each other via the rolling elements. In addition, the moving elements and the orbital element are moved relative to each other, which cause a member attached to the motion device to move.
In order to hold the rolling elements at the inner portions of the moving elements, both ends of the orbital elements in the longitudinal direction are in contact with two lids so as to be narrowed and are sealed, and both ends and the two lids are formed integrally with each other. In general, fixation of the lids to the moving elements is performed by a screw fixing. In addition, screws are screwed into screw holes that are extended and installed in a direction perpendicular to contact surfaces of the lids and the moving elements and are fixed, so as to seal the rolling elements within the moving elements.
Furthermore, in patent document 1, there is described a motion device in which the moving elements are formed in approximately cylindrical shapes and outer periphery surfaces are pivotally supported on bearings. The motion device is configured in such a manner that the bearings and the orbital element are capable of moving relatively in the longitudinal direction of the orbital element and accordingly are able to rotate relatively even in a circumferential direction of the moving elements. Thus, the degree of freedom of the motion is increased and it is possible to apply in various applications. In addition, inner peripheries of balls (bearing rolling elements) to be built in the bearings are not received by the inner rim of the bearings but are supported and rolling-driven by circumference grooves (rolling surfaces of bearing rolling element), which are formed on the outer periphery surfaces of the moving elements, so total size of the device in a diameter direction are reduced so as to be small.
[Patent Citation 1] Japanese Patent Application Laid-Open Publication No. 58-142021